It's a cosmetic option, including hurts literally no one, if its only for the PC doubly so. Removing arbitrary gender limitations of cosmetics aspects like hair and beards just opens more customisations for PC and has no effect on players who don't want to use them.
Even if you wouldn't use it yourself, does it matter if other people would enough you need to argue against it?
And really, even if the appeals to science, were scientific, this is game where player characters can be magic elves or egg laying gith. Claiming your views as science, doesn't make them any more relevant as even if that were true, the player character could be an egg laying alien gith not a mammal anyway, let alone a human.
